Horizontal Gaze Palsy, Facial Nerve Palsy, and Nystagmus Due to Dorsal Pontine Ischemia
One and half syndome; Horizontal gaze palsy; Pons; Jerk nystagmus; Upbeat nystagmus; Gaze evoked nystagmus; Facial nerve palsy; Internuclear ophthalmoplegia
Daniel R. Gold, DO, Departments of Neurology, Ophthalmology, Neurosurgery, Otolaryngology - Head & Neck Surgery, The Johns Hopkins School of Medicine
Presented here are two patients with horizontal gaze and facial palsies due to stroke. The first patient is a 60-year-old man who presented with double vision and hemiparesis due to a right dorsal pontine ischemic stroke. His exam was significant for a right horizontal gaze palsy due to right 6th nucleus involvement and right internuclear ophthalmoplegia (INO) (together, a one-and-a-half syndrome). There was also a right lower motor neuron facial palsy from a fascicular right 7th nerve palsy (also known as "eight-and-a-half syndrome" given the 7th + one-and-a-half syndrome). There was also upbeating nystagmus in upgaze due to involvement of the vertical gaze holding pathways. Convergence only improved adduction deficits mildly. The second patient is a 50-year-old man who presented with facial weakness and hemiparesis, in addition to oscillopsia due to a left dorsal pontine hemorrhage. He was unable to look left (with pursuit, saccades, or with the vestibular-ocular reflex), localizing to the left 6th nucleus; there was a left lower motor neuron facial palsy due to a fascicular 7th nerve palsy (together with the gaze palsy, an "eight syndrome"). There was also upbeat-torsional nystagmus towards the right ear, presumably due to involvement of the vertical semicircular canal pathways (mainly involving the anterior pathways given downward slow and upward fast phase). The anterior canal pathways travel through the superior conjunctivum, ventral tegmental tract, and medial longitudinal fasciculus (MLF), whereas the posterior canal pathways travel through the MLF only. Of note, in this patient's case, there was no clear INO to suggest MLF involvement. Convergence only improved his adduction deficit mildly.
Spencer S. Eccles Health Sciences Library, University of Utah